Engine soundproofing



Feb. 23, 1965 H. NAJIMIAN. JR

ENGINE SOUNDPROOFING Filed May 1, 1962 INVENTOR. #4827 IAJ/M/A/Wk transom of a boat.

, In the drawings:

I 3,17%,435 Patented Feb. 23, 1965 3,176,435 ENGINE SOUNDPROGFING Harry Naiimian, J12, Lake Bluff, lll assignor toOutboard MarineCorporation, Waulregan, llL, a corporation of Delaware Filed May 1, 1962, Ser. No. 191,486 6 Claims. (Cl. 11534) vThis invention relates generally to reduction of the noise level associated with operation of a boat engine or motor. The invention specifically relates to boats having engines mounted in the boat adjacent the transom and involves the use of a housing which is fabricated to prevent transmission therethrough of sound waves and which is disposed in substantially enclosing relation to the engine, thereby reducing the noise level in'the boat in the areas adjacent to, and immediately forward of, the engine. Such fabrication involves the use of a housing including a rigid outer shell, which is preferably curvilinearthrough-fl out, and a sound absorbing lining on the interior of the shell.

7 The invention also contemplates cushioned mounting of the housing on the boat frame to prevent transmission of vibration therebetween, and the removability of at least a part of the housing from its mounting so as to facilitate servicing of the engine.

In general, the principal object of the invention is the provision of an arrangement for substantially reducing the operating noise level of an engine mounted in a boat,

and in particular of an engine mounted adjacent to the ecome apparent by reference to the following description' and the accompanying drawings of one embodiment of the invention.

, FIGURE 1 is a partially brolren away and partially exploded view of a sound reducing arrangement embody ing various of the features of the invention;

FIGURE 2 is an eillarged view, partially in section,

I of a portion of the arrangement shown in FIGURE 1; and i FIGURE 3 isan enlargedperspective View of the'rnanc the weight of an engine if) nor in which one of the arms of the engine block extends through the sound reducing housing.

The boat 11, shown fragmentarily in FIGURE 1, inclu/des support means or a frame 13 including, at the stern,

1 a transom 15 which is either attached to or constitutes a part of a vertical boat frame portion 1'7. The vertical boat frame portion 17 serves to support, at least in part,

unit (not shown).

' Various types of engines can be employedand various arrangements areusable for supportingthe engine on the boat frame. In the preferred construction, the engine is entirely supported'by'attachment to the boatframe 13 in 'theimmediate region of the transom 15 and extends forf Wardly, being otherwise Sg enerally unsupported. More particularly, the engine block 21 has cast therewith four arms 23, two of which are secured to a horizontal member 18 of the vertical frame portion 17, and two of which are secured to the vertically. extending leg 2% of a bracket 22 which is secured to a bottom portion 24 of the boat frame which extends from and is disposed immediately adjacent the transom 15. The upstanding leg Ztl can be considered a part of the vertical frame'portion l7. Preferably, the connection of each of the mounting arms 23 to the boat frame 13 includes elastomeric pads or cushions 2-5 (see FIGURE 2) which exclude or dampen transmission of vibration from the engine 19 to the boat frame 13.

Reduction of the noise level associated with the operation of the engine 19 is obtained by substantially enclosing the engine in a housing 29 which is supported by the boat frame 13 in spaced relation'to the engine I? and is and an associated propulsion Other objects of the invention will fabricated to at least partially absorb sound waves emitted by the engine and to prevent transmission therethrough of'the non-absorbed sound waves. More particularly, the housing 29 includes an outer shell 31 which is relatively very rigid to minimize sympathetic vibration, thereby preventing actuation of the shell as a sounding board. In this connection, sounding board action can be minimized by fabricating the housing in an'overall curvilinear formation, i.el, with a minimum of flat or planar surfaces. Thus, in the disclosed construction, the housing is gen erally of cylindrical form with a forward dome shaped end. in addition, the housing 29 includes an inner lining of sound aJsorbing material 33, such as fiberglass or foamed polyurethane. v The housing 29is preferably supported by the transom 15 or vertical frame portion-J7 for forward extension in spaced enclosing relation to the engine, and is preferably constructed to afford removal of at least a part thereof to provide access to the engine 19 for maintenance, etc- In this regard, the housing 29 includes a rearwardly located,

forwardly open part or portion 35 which is mounted on the transom 15 of the verticalfrarne portion 17, and a forwardly located, rearwardly open part or portion 37 which can be releasably assembled bysuitable clips or fastening means 3 6 to'the rearward part 35. I

In order to prevent the escape of undesired sound waves from the housingwhen the parts 35' and 37 are in assembled condition, the mating margins are provided with co-operating sealingmeans for providing a generally tight joint. Since it is also desirable to prevent transmission of vibration from either housing section to the other, the sections are desirably isolated by making the sealing means elastomc'ric. More particularly, the rearward part 35 includes a resilient ring or member 41 of rubber, or like material, while the forward part 37 includes a peripheral slot or seat 43 into which the member 41 is received in generally tight engagement. The resulting relatively tight joint between the housing parts 35 and 37 also serves to retain the forwardpart in proper, spaced position to'the engine.

The housing 29 is desirably insulated from the boat frame 13 to prevent the transmission thcrebetweenof any vibration. Thus, in the preferred construction, the rear ward part 35 of the housing is-mounted on the transom 15 by means including an elastomeric ring assembly 45 (see FIGURE 2).

In the preferred construction, the elas tomeric rin'g'jinciudes two metallic rings 51 and $3, and anannular elastomeric. pad 55 bonded to eachfof the metallic rings 51 and 53 to provide, .a concentric assembly of sandwich-type constructions Both rings are tapped to re-* ceive a series of mounting screws 57 providing attachmerit of the elastomeric ring assembly 45 to th'e transom l5 andto the rearward portion35 of the housing or motor cover 29. When thus assembled, the annular elaston-ieric pad 55 between the rings 51 and 53 isolatesthe rings from each other, thereby isolating the housing 29 from the transom 15. In the case of stern drive units in which the propulsion unit is carried rearwardly of the transom 17, it is also preferred to seal the opening in the transom to prevent the escape of sound transmitting air waves. Various arrangements can be used, as for instance, a canvas connection 45 can be employed.

Although the rearward part 35 of the housing 2% is apertured to permit passage therethrough of the mounting arms 23, escape of sound transmitting'air waves through the apertures and the transmission of vibration from the engine arms 23 to the housing 29 are precluded by the use of elastomeric grommets or sealing means 47 engaging both the rearward housing part 35 and the arms 23. w

Although the disclosed housing has been described and shown as mounted on a vertical portion of the frame, the

s 3 r housing-can be partially mounted on the bottom as well as on the vertical portion of the boat frame. Additionally, the housing could be in other than a cylindrical form.

Various other of the connections normally associated With an internal combustion engine, such as for instance,

electrically supply and fuel supply, can also be passed through the housing in "gromrneted openings. Air intake and exhaust can be. provided either through the housing or through the transom, whichever is preferred in a given instance. Flexible grommets are desirably employed in association with such air intake and exhaust conduits to prevent the passage of sound transmitting air Waves and to insulate the housing or transom from'vibration associated With the engine.

Various of the features of the invention are set forth in the following claims. i

What is claimed is:

1. The cornbinati'onof a boat frame having. avertZcal portion at the stern thereoffa rigid housing which is. of

j generally curvilinear configuration throughout and which has a sound absorbing padding applied to the inner surface thereofand including a re'arwar'dly located, forwardly open v ortion extendingfrom saidvertical frameportion, .a forwardly located portion closed at its forward end and I open at its rearward end, co-operatting sealing means including a resilient member on one of said housing portions and a seat on the other of said housing portions,

and means for releasably assembling said housing pertions to each other with said resilient member engaged withsaid seat to prevent the passage of sound carrying air Waves through the connection of said. first and second housing portions, means mounting said rearwardly located housing portion to said vertical frame portion including 'elastomeric material for preventing theitransmission of vibration from said boat frame to said housing, an engine located withinaand in spaced relation to.said housing,;v means mounting said engine, at least input, to said vertical frame portion and including at least one arm extending through said housing, and elastomeric means engaging said housing and said arm for substantially preventing the transmission there etween of vibration or the passage therebetween of sound carryingair waves. I, i al combustion engine comprising vertically extending support means, a horizontally elongated engine wholly supported, adjacent 2. A mounting in a boat for an intern one ofits ends, on said support means, anda soundproofing enclosure supported on said supportrneans in horizontally extending relation to said support means'and in'enclosing relation to said engine said enclosure being free of connection'with said engine. a a

' 3. The combination in a boat-of support means inc ind ing a verticallyextendingsupport, a horizontallyelongated engine, means'mounting said engine solely adjacent one of its ends .on said support and including means for excludingthe transmission .of'vibration between said engine and said support, a sound-proofing enclosure, and

means mounting said enclosure onsaid, supportmeans in horizontally. extending relation to said supportand in' ing a generally vertical portion adjacent the sternof said excluding the transmission of vibration betweensaid enclosure and said support means.

4. The combination in a boat of support means including a vertically extending supporha horizontally elongated engine, means mounting said engine solely adjacent one of its ends on said support meansxadjacent to said vertically extending support, said engine mounting meansvincluding means for excluding the transmission of vibration between said engine and said support means a soundproofing enclosure, and means mounting'saidenclosure I on said vertically extending supportand in enclosing rela tionto and free oifcontact with said engine, said means mounting said enclosure including means for-excluding the ;transmissionof vibration between said enclosure and said supports. 1 7 I a 5. The combination in a boat ofsupport means includb oat, an internal combustion engine mounted on said support means immediately adjacentto and at least partially on said vertical portion and in otherwise unsupported forwardly extending relation to said vertical portion, and a rigid housing having an exterior of generally curvilinear configuration throughout, and mounted on said: vertical portion oi said support meansin generally enclosing,

spaced relation to said engine, said housing having its inner surface lined withiasound absorbing material and be ing mounted on said vertical portion of said support means by means for excluding the transmission of vibrationtherebetween, V

I 6. The combination'in a boat of support meansinclu' ing a, generally-vertical portionadjacent the stern of said boat, an internal combustion engine mounted on said support mear'is immediately adjacent to and-'at'le'astpartially on said vertical portion and in otherwise unsupported for: 1 wardly extending relationto said vertical portion, and a rigid housing having' an'exterior. of generally: curvi inearconfiguration-=throughout, having its inner surface lined with a sound absorbing material, extendingin' generally enclosing, spaced relation to said engine, and including first andsecond parts and means. releasably connecting saidfirst and second parts, one of said parts having thereon -a sealing member. of resilientgmaterial and the other. of said partshavingaseat for receiving said sealing member, thereby preventing the passage of. sound transmitting air waves through the connection between saidhousing parts,. said first part'beiug mounted on said vertical portion on said" support means by means for excluding the transmission of vibration therebetween.

' enclosing relation to andzfree' of contact with said engine," 'said means mounting said enclosure including means for "References {Iitedin the file of, this patent f unrrnnisrnrns PATENTS V a Dec. 11,1928 

5. THE COMBINATION IN A BOARD OF SUPPORT MEANS INCLUDING A GENERALLY VERTICAL PORTION ADJACENT THE STEM OF SAID BOAT, AN INTERNAL COMBUSTION ENGINE MOUNTED ON SAID SUPPORT MEANS IMMEDIATELY ADJACENT TO AND AT LEAST PARTIALLY ON SAID VERTICAL PORTION AND IN OTHERWISE UNSUPPORTED FORWARDLY EXTENDING RELATION TO SAID VERTICAL PORTION, AND A RIGID HOUSING HAVING AN EXTERIOR OF GENERALLY CURVILINEAR CONFIGURATION THROUGHOUT, AND MOUNTED ON SAID VERTICAL PORTION OF SAID SUPPORT MEANS IN GENERALLY ENCLOSING SPACED RELATION TO SAID ENGINE, SAID HOUSING HAVING ITS INNER SURFACE LINED WITH A SOUND ABSORBING MATERIAL AND BEING MOUNTED ON SAID VERTICAL PORTION OF SAID SUPPORT MEANS BY MEANS FOR EXCLUDING THE TRANSMISSION OF VIBRATION THEREBETWEEN. 